Rory Percival, a technical specialist, says the regulator is looking for improvements after previous failings.
Despite seeing improvements in the last report in December, Mr Percival said there were still problems to be addressed in hourly rates, cost of ongoing services, and the wide ranges of charging.
In an exclusive article written for Financial Planner magazine, which comes out tomorrow, Mr Percival said even some of the better firms could improve on their disclosure of charges.
He said: "A significant proportion of firms are still failing to correctly disclose the total cost of ongoing services in cash terms.
"Here we're referring not to the charging structure, which is usually in a terms of business, Key facts or similar document, but at a later stage when you tell the individual client what your services will cost them.
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"Around one in three firms were still failing to do this adequately. This issue was mirrored in the consumer research we commissioned which showed that many clients were unclear about what charges they were paying for ongoing services.
"It is important for firms to be clear with clients about their charges.
"The research also suggests that advisers can be more confident about disclosing their charges, as consumers value the peace of mind that comes from their arrangements being looked after and would be unwilling to give this up to avoid the associated cost."
On hourly rates, over half of firms were found to be failing to provide an approximation of how long services may take.
Mr Percival said: "Firms need to explain this in the generic disclosure document. One good practice example we have seen is a firm that gave scenario-based cost estimates relevant for its target market.
"It provided a review of pensions as an example and then listed an estimated breakdown in a clear table that showed the estimated number of hours for each role (by adviser, administrator and so on), the hourly rate for each role, a total cost for each person, and the overall total estimated cost of the service."
A quarter of firms have still been using wide ranges without explaining what would affect the client's cost, he added.